Characterization of poly(vinylidenefluoride-co-hexafluoropropylene)-based polymer electrolyte filled with rutile TiO2 nanoparticles

Various amounts of nanoscale rutile TiO2 particle are used as fillers in the preparation of poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP)-based porous polymer electrolytes. Physical, electrochemical and transport properties of the electrolyte films are investigated in terms of surface morphology, thermal and crystalline properties, swelling behavior after absorbing electrolyte solution, chemical and electrochemical stabilities, ionic conductivity, and compatibility with lithium electrode. Contrary to reported inorganic fillers showing the maximum content lower than 50 wt.%, the self-supporting polymer electrolyte films can be obtained even when using higher content of 70 wt.% rutile TiO2 nanoparticles. The physical and electrochemical properties of polymer membrane are highly improved by the addition of TiO2 nanoparticles as good dispersion of fillers, low liquid uptake but adequate ionic conductivity, excellent electrochemical stability, and stabilized interfacial resistance with lithium electrode. An emphasis should be put on the fact that the sufficient ionic conductivity obtained is led by the liquid medium within nano-pores as well as effective ion transport supported by rutile TiO2. As a result, the sample with 30–40 wt.% rutile TiO2 is confirmed as the best polymer electrolyte for rechargeable lithium batteries.